Knowledge of the composition and principles of photovoltaic power generation systems

Photovoltaic power generation systems mainly include grid connected and off grid systems. Grid connected systems transmit the electricity generated by photovoltaic systems in parallel to the national grid. Grid connected systems mainly consist of photovoltaic modules, inverters, distribution boxes, and other accessories. The off grid system operates independently and does not rely on the public power grid. The off grid system needs to be equipped with batteries and solar controllers with energy storage functions to ensure stable system power, and can provide power to the load when the photovoltaic system does not generate electricity or continuously generates insufficient power on cloudy days.

1. Photovoltaic modules

Photovoltaic modules are the core part of the entire power generation system, composed of photovoltaic modules or combinations of photovoltaic modules of different specifications cut by laser cutting machines or steel wire cutting machines. Due to the small current and voltage of a single photovoltaic cell, it is necessary to first connect it in series to obtain high voltage, then connect it in parallel to obtain high current, output it through a diode, and then package it on a stainless steel, aluminum or other non-metallic frame. Install the glass on the top and the back panel, charge nitrogen gas, and seal it. By combining photovoltaic modules in series or parallel, a photovoltaic module array, also known as a photovoltaic array, is formed.

2. Controller

The photovoltaic controller is an automatic control device that can automatically prevent overcharging and discharging of batteries. It adopts a high-speed CPU microprocessor and a high-precision A/D analog-to-digital converter. It is a microcomputer data acquisition and monitoring control system, which can quickly and real-time collect the current working status of the photovoltaic system, obtain working information of the PV station at any time, and accumulate detailed historical data of the PV station, This provides accurate and sufficient basis for evaluating the rationality of PV system design and verifying the reliability of system component quality. It also has serial communication data transmission function, which can centrally manage and remotely control multiple photovoltaic system subsystems.

3. Inverter

An inverter is a device that converts the direct current generated by photovoltaic power generation into alternating current. Photovoltaic inverters are one of the important system balances in photovoltaic array systems and can be used in conjunction with general AC powered equipment. Solar inverters have special functions in conjunction with photovoltaic arrays, such as maximum power point tracking and islanding protection.

4. Battery

Batteries are devices used to store electricity in photovoltaic power generation systems. Currently, there are four types of batteries used: lead-acid maintenance free batteries, ordinary lead-acid batteries, colloidal batteries, and alkaline nickel cadmium batteries. The widely used ones include lead-acid maintenance free batteries and colloidal batteries.

5. Working principle: During the day, sunlight shines on photovoltaic modules, generating DC voltage, converting light energy into electrical energy, and then transmitting it to the controller. After overcharging protection by the controller, the electrical energy transmitted from photovoltaic modules is transmitted to the battery for storage when needed.